This invention relates to hand-manipulated, handled devices or tools having a working end subject to substantial loading forces. More specifically, the described invention relates particularly to long-handled devices such as swimming pool skimmers and the like.
To clean areas or places which are not readily accessible to a person, such as swimming pools filled with water, it is necessary to utilize long-handled devices or appliances such as skimmers, brushes, scalers, etc. The working ends of these devices are often subjected to substantial loading. For example, commercial swimming pool skimmers may retrieve single loads of debris weighing 18 kg. (40 lb.) to 27 kg. (60 lb.). Forces produced by such loads may permanently deform the working end, break it off from its handle or break the handle. Additionally, the dead weight effect of the forces to which these devices are subjected can (and do) adversely affect the ability of a worker to manipulate the presently-available devices.
When utilizing the described appliances, it is often desirable to be able to manipulate the handle so that the working end can be bent away from its normal plane (without distorting the working end itself) to provide a scraping action or to maneuver the working end around corners, over curved surfaces, etc. Unfortunately, even a few bendings often result in breaking the frame.
It is also desirable that the working end return to its normal plane after being displaced therefrom by a worker (or by loads to which it may be subjected) so that substantially no permanent set is produced in the appliance material even after numerous bendings. When the frame does not return to its normal plane, the worker must take the time to apply sufficient pressure to force it to do so.
Numerous designs for swimming pool appliances have been made and used -- some with greater success than others. However, there are presently no such appliances which can satisfy the previously-discussed problems. This is particularly true in the commercial field where these problems are magnified due to the greater use (and abuse) to which these appliances are subjected.
Various designs and constructions are disclosed in the following U.S. Pat. No. 3,368,686, issued Feb. 13, 1968, entitled "Swimming Pool Scoop and Skimmer"; No. 3,220,037, issued Nov. 30, 1965, entitled "Swimming Pool Cleaning Equipment"; and No. 2,706,664, issued Apr. 19, 1955, entitled "Handle Mounting for Net Frames."
U.S. Pat. No. 3,368,686 describes a swimming pool skimmer which includes a loop having a pair of radially-extending ends inserted in parallel into one end of a tubular handle and held therein by fasteners or other suitable means. Depending upon the thickness of the loop material, the loop either cannot be bent about its ends out of its normal plane or, if it can be so bent, it will break after relatively few such bendings because the connection between the handle and the loop does not provide sufficient flexibility and strength to absorb the stresses of multiple bending. Additionally, the disclosed connection presents manufacturing and assembly problems if a fastener is required. If the loop ends are retained in the handle by crimping the latter without using fasteners, those ends are subject to being pulled out during use.
U.S. Pat. No. 3,220,037 discloses a swimming pool skimmer in which the handle is rigidly connected to a flat ring structure by a press-fitted plug which serves to wedge parallel ends of the ring in the tubular handle. The resulting rigid assembly resists bending movement of the ring structure away from its normal plane. Additionally, if sufficient force is exerted to bend the frame away from its normal position, the frame will break.
U.S. Pat. No. 2,706,664 discloses a swimming pool skimmer in which the net-supporting frame is connected to a handle through a cast head at one end thereof. Free ends of the frame when in place extend through the sides of the head and are bent at right angles into longitudinal parallel relation to each other. They are retained in that position by removable, sleeve-type keys. The resulting connection (between frame and handle) is relatively stiff even though the frame may be formed from spring wire. Although the described assembly provides for relatively easy assembly and disassembly and even though it permits some bending of the frame away from its normal position, it does not have significant memory (returnability) and the frame will break after relatively few bendings so that replacement of the frame then becomes necessary. Additionally, the described assembly requires substantial close tolerance machining which can be expensive.
Another swimming pool skimmer design which has been manufactured for a number of years comprises a generally rectangular frame which may be made from spring wire and which has aligned ends held in place within a casting (connected to a handle) by rivets. This design resists bending of the frame and, if subjected to sufficient bending force, will break.
As will be understood from the foregoing discussion of the prior art, there remains a need for a hinge which will interconnect a working element and a handle to permit bending of the former at the hinge so that the working element can be bent away from or urged out of its normal plane, yet which will return the working element to its normal plane when the bending forces are removed. At present, it is estimated that up to 80% of the swimming pool skimmer market constitutes replacement skimmers for those which have broken (usually as the result of an inability to withstand bending forces).